Does resistance to filarial reinfections become leaky over time?

Strategies for the control of human parasitic diseases such as onchocerciasis and lymphatic filariasis require an understanding of how the parasite successfully infects and persists in humans. Despite the fact that the vast majority of infective larvae are eliminated after infection, this 'protection' is far from being an all-or-nothing response. The hypothesis presented here, which is based on epidemiological observations, suggests that the resistance against filarial parasites includes a time-dependent component, probably caused by an early immune response with short-term memory. Validating this hypothesis requires experimental studies with a longitudinal component. Such experiments would help to clarify whether the infection can be controlled by vaccination strategies at all.